Energy Consumption: Bikes v Cars

Bicycling requires 35 kcal/mi. Cars require 1,860 kcal/mi. [Both of
those figures are from Marcia Lowe of the World Watch Institute.] Someone
here suggested it takes 10 kcal of energy to produce 1 kcal of food.
[This is inflated. I remember hearing it takes just under 5 kcal of
energy to grow 1 kcal of vegetarian food, sorry I don't have the
reference in my possession. Of course, a vegetarian diet is a whole
other argument we can get into :) .] Yet another person mentioned there
is ~25% efficiency in converting eaten food to useful work. [Note:
that's kcal eaten to joules of work; I think Ms Lowe's calculation above
is different, referring to kcal eaten to go a mile.]
The average diet is about 2,000 kcal/day.

Either way you look at it, bikes are more efficient. Now, factor in that
both the cyclist and auto driver are going to eat about 2,000 kcal
anyway. To go a mile, I'd only have to eat between 2% and 7% more food, if I eat
anymore at all.

This page was written by Daniel Convissor as a posting to ba.transportation on
3 July 1994